超顺磁性氧化铁灌注T_2WI诊断超急性脑缺血的实验研究

目的观察国产超顺磁性氧化铁（ＳＰＩＯ）灌注Ｔ２ＷＩ诊断超急性期脑缺血的可行性。方法正常大鼠５只和右侧大脑中动脉闭塞（ＭＣＡＯ）大鼠２６只，行ＳＰＩＯ灌注前后Ｔ２ＷＩ，后者在ＭＣＡＯ后４０～５０分钟行ＭＲ检查。ＭＲ检查后４只行墨汁灌注检查，６只在ＭＣＡＯ后２４小时行ＭＲ复查和病理检查。ＳＰＩＯＩ颗粒直径２０ｎｍ、ＳＰＩＯＩ颗粒直径６～９ｎｍ，剂量为０６ｍｍｏｌ／ｋｇ。采用ＳＰＩＯＩ做了６只、ＳＰＩＯＩ做了２０只灌注检查。结果在ＭＣＡＯ后５０分钟，平扫Ｔ２ＷＩ仅３７％表现右侧大脑中动脉（ＭＣＡ）供血区信号稍高；两种型号的ＳＰＩＯ灌注后１００％或８０％的右侧ＭＣＡ供血区呈相对高信号，与墨汁灌注检查的灌注缺损区及ＭＣＡＯ后２４小时复查Ｔ２ＷＩ的高信号范围一致。病理检查证实右侧ＭＣＡ供血区的缺血、梗死。在剂量相同情况下，ＳＰＩＯＩ灌注Ｔ２ＷＩ显示缺血区与非缺血区的对比度明显高于ＳＰＩＯＩ。结论ＳＰＩＯ相当于一种阴性造影剂，国产ＳＰＩＯ“灌注”常规Ｔ２ＷＩ可以诊断血管闭塞５０分钟的急性脑缺血，ＳＰＩＯＩ灌注的诊断效果优于ＳＰＩＯＩ。

Experimental study on perfusion T2 weighted imaging with superparamagnetic iron oxide in hyperacute cerebral ischemia

Objective To determine the feasibility of superparamagnetic iron oxide (SPIO) perfusion T2WI for detecting hyperacute cerebral ischemia ZMethods Thirtyone rats were included 26 rats underwent right middle cerebral artery occlusion (MCAO) by Zea Longa's method, the other 5 rats were used as normal control group At 4050 minutes after the procedure of MCAO, pre and postperfusion of SPIO T2WI were performed SPIOI particle diameter 20 nm, SPIOII particle diameter 6-9 nm dose 06 mmol/kg iv(SPIOI 6/26 rats and SPIOII 20/26 rats) In 6 of 26 MCAO models, T2WI was obtained 24 hours after MCAO ResultsBZIn 50 minutes after MCAO, the findings of ischemic changes were either absent or subtle (37%) on T2WI before SPIO administration, but became marked on SPIOI perfusion T2WI (100%) and SPIOII perfusion T2WI (80%) The relative higher signal area on SPIO perfusion T2WI corresponded exactly to the area of definite ischemia seen on the black ink perfusion pathology, and also the infarction areas on 24 hours images seen on T2WI and HEstained brain slices Conclusions The results suggested that SPIO perfusion T2WI has the capability of detecting early stage of cerebral ischemia within 1 hour after cerebral artery occlusion SPIO serves as a negative contrast media in T2WI The contrast effect of SPIOI perfusion T2WI is better than that of SPIOII in hyperacute cerebral ischemia